This invention relates to an electrical connector adapted to be able to electrically connect a plurality of electric contacts and a plurality of electric contact elements at a time, and more particularly to an electrical connector including first and second connectors adapted to prevent any solder of the first connector from adhering to contact portions of the second connector.
We have ever proposed an electrical connector adapted to be able to electrically connect a plurality of electric contacts and electric contact elements at a time in U.S. patent application Ser. No. 09,366,832 filed Aug. 4, 1999, U.S. Pat. No. 6,220,871. The proposed electrical connector will be explained with reference to FIG. 6.
Referring to FIG. 6, the electrical connector 60 includes a first connector 10 (Ball Grid Array or BGA) and a second connector 50 (which is a socket connector to be connected to BGA elements or the like). When the first and second connectors 10 and 50 are brought into detachable abutment against each other, a plurality of electric contacts 12 made of solder in the form of spherical protrusions provided on one surface of the connector plate 11 of the first connector 10 are electrically connected to a plurality of electric contact elements 52 provided on one surface of the board 22 of the second connector 50. The first and second connectors 10 and 50 are detachably connected to each other with the aid of a plug and socket mechanism (not shown).
The connector plate 11 of the first connector 10 is made of a ceramic or hard resin substrate or board having a rigidity, on one surface of which are provided a plurality of electric contacts 12 of solder (PbSn) in the form of spherical protrusions. These electric contacts 12 are formed by reflow-soldering solder balls arranged on lands of a hard resin board.
The plurality of electric contact elements 52 are provided on one surface of the board 22 so as to be electrically connected to the electric contacts 12 of the first connector 10. As shown in FIG. 6, the electric contact elements 52 are provided on conductors 26 on the board 22 made of a flexible printed card (FPC) or the like which is formed with U-shaped slits 24 around the conductors 26 to elastically support the electric contact elements 52 by small tongue-shaped pieces 36. With this construction, the elastic support of the electric contact elements accommodates any differences in height between the electric contacts 12 of the first connector 10. The electric contact elements are treated with a surface treatment such as gold plating because they are electrically contacting portions.
The second connector 50 is used for inspecting the first connector 10 so that the electrical contact therebetween amounts often to several thousand times or more. Consequently, the electrical connector of this type suffers from the following disadvantages.
Referring to FIG. 7, when the electric contacts 12 of the first connector 10 and the electric contact elements 52 of the second connector 50 have been contacted with each other several hundred times, the solder (PbSn) forming the electric contacts 12 tends to adhere (as shown at 54) to the treated surfaces of the electric contact elements such as plated surfaces with gold, causing incorrect contact therebetween.
Owing to such an adherence of the solder 54 (FIG. 7) to the treated surfaces of the electric contact elements 52, removal of the adhered solder therefrom is needed by the use of a brush every several hundred times or thousand times of the contact between the electric contacts and the electric contact elements. However, the removal of the adhered solder by brushing is not an easy matter if not impossible. In order to remove the adhered solder more completely, it is required to increase the times of the brushing operation, which also increases the man-hour of the operation of the electrical connector, resulting in increased cost of operation.
It is an object of the invention to provide an improved electrical connector which eliminates all the disadvantages of the prior art described above and which minimizes the adherence of solder or oxide impurities to treated surface layers of electric contact elements even after repeated contacts between electric contacts and the electric contact elements of first and second connectors more than several thousand times.
In order to accomplish the above object, in an electrical connector including a first connector having a connector plate and a plurality of electric contacts provided on one surface of said connector plate, and a second connector having a board and a plurality of electric contact elements provided on conductors arranged on said board, said board formed with slits around said conductors to support said conductors and the like elastically by parts of said board surrounded by said slits, said first and second connectors being brought into detachable abutment against each other to electrically connect said electric contacts and said electric contact elements of said first and second connectors, according to the invention said electric contact elements of the second connector each comprise at least one ridge having a sharp crest thereon facing to said electric contact of said first connector.
The ridge or ridges preferably extend in parallel with the direction in which the electric contact of the first connector slides on the electric contact element of the second connector.
The ridge or ridges preferably have sharp crests.
In a preferred embodiment, the ridge or ridges have a height of 0.1 mm to 0.2 mm from the surface of the electric contact element.
In one embodiment, the electric contact elements of the second connector each comprise a plurality of ridges thereon extending in parallel with the direction in which the electric contact of the first connector slides on the electric contact element of the second connector to form a wave shape.
The number of the ridges of one electrical contact element is decided in consideration of a positional deviation between the electric contact element and the mating electric contact of the first connector.
Preferably, the ridge or ridges are formed in a manner that after providing a protection covering layer on the conductors, the protection covering layer is formed with one slit or plural slits at a location corresponding to each of the conductors and the slit or slits are then plated with a metal to fill the slit or slits with the metal so as to form the electric contact element and further to form the ridge or ridges by continuing the plating with the metal.
The board of the second connector is preferably provided with at least one elastic material layer such as silicone on the opposite side of the conductors to ensure the elastic supporting of them.
The electrical connector according to the invention provides the following significant effects.
(1) According to the invention the projecting ridge or ridges are provided on the surfaces of the electric contact elements, thereby making it possible to remove or scratch off the solder adhered to the electric contact elements in the preceding contact operations between the electric contacts and the electric contact elements without requiring any other particular precaution.
(2) According to the invention the ridge or ridges extend in parallel with the sliding movement of the electric contacts of first connector so that the solder debris attached to the electric contact elements in preceding contact operations can be removed forwardly with more certainty.
(3) According to the invention the ridge or ridges can be easily formed by progressively plating with a metal in slits formed in a protection covering layer provided on conductors. In the event that the crests of the ridges have been worn off, the ridges can be reformed by plating with the metal to regain the initial function of the ridges.
The invention will be more fully understood by referring to the following detailed specification and claims taken in connection with the appended drawings.